Author: harish2704

simple-db-migrator.php

@@ -0,0 +1,274 @@
+<?php
+/*
+ * ॐ  Om Brahmarppanam  ॐ
+ *
+ * schema/migrator.php
+ * Created at: Thu Jul 20 2022 19:34:40 GMT+0530 (GMT+05:30)
+ *
+ * Copyright 2022 Harish Karumuthil <harish2704@gmail.com>
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ *
+ */
+
+require_once __DIR__ . "/../vendor/autoload.php";
+
+// Load database credentials from database.php 
+// where  $dbPass, $dbName, $dbHost, $dbUser are defined.
+include __DIR__ . "/../database.php";
+
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Logger\ConsoleLogger;
+use Symfony\Component\Console\Application;
+
+$MIGRAION_ROOT = __DIR__ . "/migrations";
+$L;
+
+class MigrationItem
+{
+  /**
+   * @param $v {int} Version number
+   */
+  public function __construct($v)
+  {
+    global $MIGRAION_ROOT;
+    $this->v = $v;
+    $this->upFile = sprintf("%s/up/%03d.sql", $MIGRAION_ROOT, $v);
+    $this->downFile = sprintf("%s/down/%03d.sql", $MIGRAION_ROOT, $v);
+  }
+
+  public function getSQL($fname)
+  {
+    return file_get_contents($fname);
+  }
+
+  public function getUpSQL()
+  {
+    return $this->getSQL($this->upFile);
+  }
+
+  public function getDownSql()
+  {
+    return $this->getSQL($this->downFile);
+  }
+}
+
+class Migrator
+{
+  public function __construct()
+  {
+    global $dbPass, $dbName, $dbHost, $dbUser, $L;
+    $this->db = new PDO("mysql:host=$dbHost;dbname=$dbName", $dbUser, $dbPass);
+    $this->L = $L;
+  }
+
+  private function runSQLTransaction($sql)
+  {
+    $sql = "BEGIN;
+    $sql
+      COMMIT;";
+
+    $this->L->debug("Runing SQL");
+    $this->L->debug($sql);
+    return $this->db->query($sql);
+  }
+
+  /*
+   * Get array of pending version numbers
+   * @return int[]
+   */
+  public function getPendingMigrations()
+  {
+    $lastRanMigration = $this->getLastRanMigration();
+    $availableMigrations = $this->getAvailableMigrations();
+
+    if ($lastRanMigration == 0) {
+      return $availableMigrations;
+    }
+
+    $lastMigrationIdx = array_search($lastRanMigration, $availableMigrations);
+
+    if ($lastMigrationIdx === null) {
+      throw new Exception(
+        "Inconsistent state: Last migration is missing in filesystem"
+      );
+    }
+    return array_slice($availableMigrations, $lastMigrationIdx + 1);
+  }
+
+  /*
+   * Get array of available verion numbers
+   * @return int[]
+   */
+  private function getAvailableMigrations()
+  {
+    global $MIGRAION_ROOT;
+    $files = scandir("$MIGRAION_ROOT/up");
+    $out = [];
+    foreach ($files as $fname) {
+      $match = [];
+      $matches = preg_match('/^([0-9])*.sql$/', $fname, $match);
+      if ($matches > 0) {
+        $out[] = (int) $match[1];
+      }
+    }
+    sort($out);
+    return $out;
+  }
+
+  /*
+   * @return int
+   */
+  private function getLastRanMigration()
+  {
+    try {
+      $result = $this->db
+        ->query(
+          "SELECT version from db_migrations order by version desc limit 1",
+          PDO::FETCH_ASSOC
+        )
+        ->fetchAll();
+    } catch (Exception $e) {
+      if ($e->errorInfo[0] == "42S02") {
+        throw new Exception(
+          "db_migrations table doesn't exists. Please run setup"
+        );
+      }
+    }
+    if ($result) {
+      return $result[0]["version"];
+    }
+    return 0;
+  }
+
+  public function runUp()
+  {
+    $this->L->warning("Running up");
+    $pendingMigrations = $this->getPendingMigrations();
+    $this->L->warning("Pending migrations " . json_encode($pendingMigrations));
+    foreach ($pendingMigrations as $migrationV) {
+      $this->L->warning("Running migration " . $migrationV);
+      $migrationItem = new MigrationItem($migrationV);
+      $sql = $migrationItem->getUpSQL();
+      $this->runSQLTransaction($sql);
+      $this->db
+        ->prepare(
+          "INSERT INTO db_migrations
+          (version, created_at, up_sql, down_sql) VALUES (?, now(), ?, ?)"
+        )
+        ->execute([$migrationV, $sql, $migrationItem->getDownSql()]);
+    }
+    $this->L->warning("executed all pending migrations");
+  }
+
+  public function setup()
+  {
+    $this->L->info("Creating db_migrations table ...");
+    return $this->db->query("
+      CREATE TABLE db_migrations (
+        version int unsigned NOT NULL,
+        created_at datetime DEFAULT NULL,
+        up_sql longtext DEFAULT NULL,
+        down_sql longtext DEFAULT NULL,
+        PRIMARY KEY (version)
+      )");
+  }
+
+  /*
+   * @return string
+   */
+  private function getDownSqlFromDb($v)
+  {
+    $res = $this->db
+      ->query(
+        "select down_sql from db_migrations where version = $v",
+        PDO::FETCH_ASSOC
+      )
+      ->fetchAll();
+    return $res[0]["down_sql"];
+  }
+
+  public function runDown()
+  {
+    $this->L->warning("Rolling back last migration ...");
+    $lastRanMigration = $this->getLastRanMigration();
+    if (!$lastRanMigration) {
+      throw new Exception("There is no migration to rollback");
+    }
+    $this->L->warning("last migration is $lastRanMigration");
+    $migrationItem = new MigrationItem($lastRanMigration);
+    $downSqlFromDisk = $migrationItem->getDownSql();
+    $downSqlFromDb = $this->getDownSqlFromDb($lastRanMigration);
+    if ($downSqlFromDisk != $downSqlFromDb) {
+      $this->L->error(
+        "rollback sql stored in db does not match with the sql in filesystem"
+      );
+      $this->L->error("SQL from db");
+      $this->L->error($downSqlFromDb);
+      $this->L->error("SQL from filesystem");
+      $this->L->error($downSqlFromDisk);
+      $this->L->error("Please manually fix this error and run again");
+      throw new Exception(
+        "rollback sql stored in db does not match with the sql in filesystem"
+      );
+    }
+
+    $this->runSQLTransaction($downSqlFromDisk);
+    $this->db
+      ->prepare("DELETE FROM db_migrations WHERE version = ?")
+      ->execute([$lastRanMigration]);
+
+    $this->L->warning("Rollback completed");
+  }
+}
+
+class DbMigrate extends Command
+{
+  protected function configure()
+  {
+    $this->setName("db:migrate");
+    $this->setDescription("Migrate DB to the latest version.");
+    $this->addOption(
+      "setup",
+      "s",
+      InputOption::VALUE_NONE,
+      "Create db_migrations table in db"
+    );
+    $this->addOption(
+      "down",
+      "d",
+      InputOption::VALUE_NONE,
+      "Roll back last migration"
+    );
+  }
+
+  protected function execute(InputInterface $input, OutputInterface $output)
+  {
+    global $L;
+    $L = new ConsoleLogger($output);
+    $L->info("Starting migrator");
+    $runSetup = $input->getOption("setup");
+    $migrator = new Migrator();
+
+    if ($runSetup) {
+      $migrator->setup();
+    }
+    if ($input->getOption("down")) {
+      $migrator->runDown();
+    } else {
+      $migrator->runUp();
+    }
+    return 0;
+  }
+}
+
+$application = new Application("Migrator", "1.0.0");
+$command = new DbMigrate();
+$application->add($command);
+$application->setDefaultCommand($command->getName(), true);
+$application->run();